W

White
A term used within the diamond trade that describes the colourless nature of a diamond. Generally speaking, the more 'white' a stone, the greater its value.

T

Table
The large facet on top of the crown of a diamond.

Treated
A term used to describe a diamond that has been altered (other than by normal cutting and polishing) in order to change its appearance. 

S

Sawing
The method by which the diamond is cut against the grain.

Scaife
The horizontal, rotating mill or grinding wheel on which a diamond is polished..

Sights
The term given to the special sales held by D.T.C. 10 times a year where parcels of rough diamonds are presented the D.T.C. sight-holders (of which there are approximately 138 worldwide) for purchase.

Spread Stone 
A brilliant cut diamond with a large table (over 60%) and a thin crown height.

R

Rough
The term given to crystals of diamonds as they are found in mines.

Rough Girdle 
A grainy or pitted girdle, often including small nicks or scratches.

Round Brilliant Cut
The most common style of cut diamond around today. It includes 58 facets and makes the most efficient use of light in order to maximise fire and sparkle.

Q

Quality
This refers to the degree of excellence of a diamond as measured by the factors that determine it's worth, i.e., its cut, carat weight, clarity and colour.

P

Pavilion
The bottom part of a polished stone below the girdle.

Pique or PK
A term meaning a lower clarity grade with inclusions which are visible to the naked eye.

Point
One hundredth of a carat. For example a 0.35ct stone is also known as a 35 pointer.

Princess Cut
A square shaped, modified brilliant cut diamond. [Link Here Soon!] to learn more about diamond shapes

O

Open Culet 
A culet that is larger than normal.

Open Table
A larger than normal table facet.

Open Cast or Open Pit
Mining from the surface.

N

Natural
A part of the natural surface of a rough diamond left on the girdle of a polished stone. This is often the sign of a good cutter aiming for maximum weight retention.

Near-Gem
A certain quality of rough diamonds between gem and industrial that could be used as either depending on the nature of the markets.

M

Marquisse Shape
A boat shaped diamond with curved sides that meet to form a point at either end. [Link Here Soon!] to learn to more about diamond shapes.

Melee
Polished diamonds up to about 0.25ct. in weight.

Mishkal
An early Moslem weight for gems equal to 36.4 carats.

J

Jager
A diamond with a slight blue tint, named after the Jagersfontein mine in South Africa. The blue may be due to strong fluorescence.

I

Illusion Setting
This is a mount used for small stones where a reflecting plate is used within the setting to make it look larger.

Industrial Diamond
A diamond which is not of gem quality that is used for industrial applications such as drilling or cutting. Approximately 90% of diamonds are used for industrial applications. 

H

Hardness
Hardness scales depend on the relative hardness of one substance to another. The Mohs 'scratch hardness' scale is based on the fact that any mineral on a numbered scale will scratch those of lower numbers and be scratched by those of higher numbers. Diamond is the hardest naturally occurring substance ever found and features at the top of this scale.

Habit
This is the term used to describe the shape of crystallisation favoured by a mineral. For diamond it is the octahedron.

G

Gem Quality
A diamond that is of gem quality, i.e., one that possesses desirable properties. Only about 10% of all diamonds found are of gem quality.

G.I.A.
The Gemmological Institute of America.

Girdle
The girdle is the outer edge of the diamond between the crown and the pavilion. It can be faceted, polished or smooth. The girdle thickness varies from stone to stone and can range from extremely thin to extremely thick. There are four grades in the middle of this range that are considered to be optimal.

Girdling
Another name for bruting or rounding where the rough stone is rounded and the girdle is formed.

Gletz (also spelled glets, glatts)
Another name, of Dutch origin, for a feather.

Grain lines
These can appear within a diamond as faint parallel lines and can mostly only be observed using magnification.

F

Facet
These are the polished surfaces of a diamond. The way that light moves through a diamond and interacts with the facets give a diamond its fire and sparkle.

Fancies
Fancies are attractively coloured diamonds. Diamonds can be coloured red, emerald green, sapphire blue, pink, black, orange or brown.

Fancy Shapes
A diamond whose shape is anything but round, i.e., heart, pear or oval.

Feather
A feather is a type of inclusion or flaw within a diamond. It is often white and feathery in appearance.

Fire
When white light enters a diamond, it is dispersed and refracted into a spectrum of colours that can be seen by the naked eye. The term fire refers to the intensity of this dispersion of light.

Fluorescence
Fluorescence is a form of lumination that is created when a diamond is exposed to low or high wave ultraviolet radiation. Faint fluorescence will rarely detract from a diamond's beauty and cannot normally be seen or separated by the naked eye. Strong fluorescence can sometimes improve the appearance of diamonds that possess colour.

Fracture
A crack on the surface of a diamond

E

Emerald Shape
An emerald cut diamond is rectangular in shape with cut corners. [Link Here Soon!] to learn more about an emerald cut diamond.

Extra Facet
A small facet which is not required by the cut, often applied in order to remove a small blemish.

D

Diamond
Diamond is the hardest known natural substance and is composed of pure, crystallised carbon. Diamonds are mined in the rough form and are then cut and polished in order to reveal their fire and brilliance.

Dop
The holder used for a diamond being polished.

Double Rose-Cut
This is a cut with a rose on the top and bottom. Also called a double rosette.

C

Carat 
Refers to the weight of a diamond. One carat is equivalent to 0.2grams. A carat can also be divided into 100 'points'. A 50 point stone being the same as a 1/2-carat. [Link Here Soon!] to learn more about the carat weight of a diamond.

Certification 
On the whole, diamonds bought from the high street should be certified by an independent laboratory. There are many of the these laboratories throughout the world. [Link Here Soon!] to find out more about the certification of diamonds.

Clarity 
Refers to the amount of inclusions present within a diamond and also to the amount of blemishes present on its surface. These natural imperfections are often referred to as 'nature's fingerprints'. They will mostly not affect the beauty of a diamond but will almost always affect the price. A stone with no imperfections under 10x magnification is termed 'flawless' by the GIA which is slightly misleading as in reality there is no such thing as a flawless diamond as long as you use high enough magnification. [Link Here Soon!] to learn more about how clarity affects a diamond's value.

Colour
Diamonds are graded on a colour scale which was established by the Gemmological Institute of America (GIA). This scale ranges from colourless, 'D' to tinted yellow, 'Z'. The more colourless a diamond, the greater its sparkle. [Link Here Soon!] to learn more about the colour of a diamond.

Cross-Cutter
The craftsman who puts on or grinds the first 16 facets..

Crown
This is the upper portion of a diamond above the girdle

Culet
This is the bottom point of a diamond. On some stones it can be polished into a surface or facet, whereas on others, it may be left as a point.

Cut
Cut refers to the proportions, symmetry and polish of a diamond. The proportions are the size and angle relationships between the facets and other surfaces and are expertly manipulated by the diamond cutter. The more successful the cutter is in balancing these factors, the more valuable the stone will be. Cut also refers to the shape of the diamond, i.e., emerald cut or princess cut. [Link Here Soon!] to learn more about the cut of a diamond.

B

Baguette Shape 
A rectangular shaped diamond with step like facets. If the two longer sides taper inwards, it is known as a 'tapered baguette'. [Link Here Soon!] to learn about diamond shapes.

Blemishes
This refers to the amount of external marks on a stone. [Link Here Soon!] to learn more about blemishes and how they affect the clarity of diamonds.

Bow Tie
This is the dark, bow tie shape which can be seen in the table of pear, oval and marquisse shaped polished diamonds.

Brilliance 
Refers to the fire of a stone or the amount it sparkles when light is reflected through its facets.

Brillianteer
The craftsman responsible for putting on and polishing the final 40 facets of a diamond after the cross-cutter's work.

Bruting
This is the process by which the diamond's girdle is formed, the basic dimension of the finished diamond.